Great suggestions, THANKS. While I've got about everything there is on Model 70s, I have very little in my gun library about the US sniper program, equipment, etc. Since there are several Senich titles, I appreciate the advice on which to consult first.
Regarding Lyman sights on civilian Winchester M70 target rifles:
-- All Model 70 National Match, Target, and Bull Guns from 1936-1963 had the "Lyman-type" telescope sight mounting blocks that have a radius cut on top to permit unobstructed use of metallic sights with the scope removed. A two-position block on the barrel and a single position block on the front receiver ring (just like MescaBug's photo below). The front block was different heights for the different target configuration due to differences in barrel dimeter. Over the years MANY of these block got replaced by "Unertl-type" blocks that are flat on top, but you can periodically find the right ones on Ebay.
-- The earliest Target (Medium Heavy barrel) rifles (1936-1937) were factory equipped with Lyman 17A globe front and Lyman 48WJS receiver sights (same receiver sight used on the sporting rifles of the time). Mostly, these are the ultra-rare "first variation" Target rifles with an integral front sight ramp that were produced from barrel blanks manufactured for Model 54 production. I have one of these (S/N 3339) and it does have the Lyman 48WJS. Several examples are pictured in Rule's Model 70 book.
-- From the advent of the so-called "second variation" Medium Heavy target barrel (1937-1952) where the muzzle end was dovetailed to accept a drift-in ('AK' height) block, the standard front sight became the Lyman 77R and receiver sight the Lyman 48WH. The only real difference between the 48WJS and 48WH is that there is a 'step-up' in the elevator cross bar carrying the aperture. It is worth noting that the Lyman 48 sights made before 1947 required inletting the stock, while the so-called 'half-block' design produced after 1947 does not. So if the gun you are looking at is pre-war or transition (clover leaf tang - below about S/N 80,000) then a cut-out in the stock IS factory original. Any 'oval tang' target (or sporting) rifle with wood removed for a receiver sight is probably owner-modified.
-- Technically, the Target and Bull Gun were "discontinued', i.e. not catalogued, between 1952 and 1955, but as far as I can tell many were made/sold anyway. That would include a lot of the Van Orden rifle sales listed in Chandler. Sights would be Lyman 77R front and half-block Lyman 48WH receiver.
-- When the Target and Bull Gun were reintroduced to the catalog (as an aside, the National Match rifle, with its standard weight barrel and Marksman stock, was never dropped), the so-called 3rd variation Medium Heavy target barrel came along (1955-1963). This differed only in that the cross dovetail cut at the muzzle was replaced by two 6-48 tapped holes. The only chamberings offered by this time were 30-06 and 243 WIN. The 1955 and later guns were catalogued as sold WITHOUT METALLIC SIGHTS, but of course could be ordered with them. Example being the Van Orden S/N 351439. The default sights, if so ordered, would have been the same Lyman 77R and half-block 48WH.
Hope this is useful.